Certain types of fittings require an annular gasket located between the end surfaces of adjacent fittings to provide a leak-free connection. These fittings are generally referred to as "face seal" fittings. Elastomeric O-ring seals have received widespread acceptance as being appropriate for this application, as the seals are easily and inexpensively formed, generally conform to the adjacent surfaces, and can withstand a wide range of system pressures. The O-ring seal is received within a groove formed in the end surface of at least one of the fittings, and the fittings are assembled such that the seal is compressed against the end surface of the adjacent fitting. The pressure of fluid within the fitting acts against the seal ring to form a pressure seal against the opposing fitting surface.
Various groove designs in the fitting end face have been developed in an attempt to allow easy assembly of the seal in the groove, maintain proper orientation of the seal, and to prevent the seal from falling out of the groove as the fitting end faces are brought together. One common technique is to form an annular groove or channel with relatively straight cylindrical sidewalls and a flat annular end wall in the end surface of the fitting, and to locate the O-ring seal in this groove. Another groove design, commonly referred to as a half-dovetail groove, has one sidewall, typically the outer sidewall, tapered inwardly toward the other sidewall (i.e., toward the central axis of the fitting). The seal is radially compressed to fit over the dovetail portion of the groove, and expands when it is fully seated within the groove. Full dovetail grooves are also known, where both sidewalls taper inwardly toward each other and the seal cross section is similarly compressed when inserted into the groove and expands back to its original shape when the seal is fully seated within the groove.
Assembling an O-ring seal or other type of annular gasket within the above-described grooves can pose certain challenges. If the groove is merely a standard annular groove, the O-ring can be easily located within the groove by merely pushing the seal squarely against the fitting end surface. This type of groove however, can allow the O-ring to fall out when the fittings are separated, and so is not appropriate for certain applications. If the groove is a half-dovetail or full-dovetail groove, the O-ring must be compressed in some manner to initially locate the seal within the groove. While this type of groove retains the O-ring within the groove even if the fitting end faces are separated, care must be taken not to rip, twist or otherwise damage the O-ring along the groove during insertion. The assembly of O-rings in these types of grooves therefore has to be more carefully controlled.
Assembling an annular seal such as an O-ring into the above-described grooves can be accomplished by hand, in which case care can be taken in order to locate the O-ring in the groove without damaging the seal. However, such hand-assembly can be slow, labor-intensive and expensive. Certain tools have been developed in an attempt to provide a more automated technique for quickly and consistently locating a seal within a fitting groove. U.S. Pat. No. 3,981,066, for example, shows inner and outer annular members defining an annular funneled shoot, and an intermediate push ring which pushes the O-ring through the restricted opening defined between the sidewalls, where the O-ring can then expand into its normal shape when it is fully seated within the groove. The groove has a full dove-tail design. The tool has an inner annular shoulder which is received within the inner diameter of the seat ring to locate the tool with respect to the fitting.
Other assembly tools for locating an O-ring within an annular groove (non-dovetail design) include Japanese Patent Abstract No. 4-175578 and U.S. Pat. No. 3,289,286.
While the above tools might be appropriate for certain applications, it is believed that these tools can suffer certain drawbacks, and do not all provide a useful tool which is easily located over a fitting, has a minimum of movable parts, and can be quickly and consistently used to locate an O-ring within a groove without damaging the O-ring. The tools described above are also not designed specifically to locate O-rings in half dove-tail grooves, which account for a significant and expanding portion of the fitting market. Other tools are known for locating spring retaining rings and packing cord around a cylinder (such as the neck of a milk bottle), or a tube, however, it is believed these tools are generally inapplicable to face seal-type fittings of any type. As such, it is believed there is a demand in the industry for an O-ring assembly tool which overcomes the above-described drawbacks, and is particularly suited for locating O-rings in half-dove tail grooves.